<!DOCTYPE html>
<html lang="zh_CN">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<button id="btn">点击我弹出一个提示框</button>
</body>
<script type="text/javascript">

    var a = 1;
    var b = 2;

    setTimeout(function () {
        console.log('setTimeout call');
    }, 1000);

    var c = a + b;
    console.log(c);


</script>

</html>
